AGARD - STRES - Battery

In its committee for psychological issues, the Advisory Group for Aerospace Research and Development (AGARD) has recommended a computer supported test battery for the examination of the mental performance: the STRES battery (Standardized Tests for Research with Environmental Stressors). Most of the tasks are based on the CTS (Criterion Task Set) battery, which was developed for the then popular C64 computer.

The individual tasks are offered via PC; the tasks are processed either by use of the keyboard/mouse of the PC or by special input elements. This enables us to log the single reaction time besides the error quota and the total input that is registered by paper-pencil-tasks. The sequence of the induividual questions is usually self-paced, i.e. answering one question directly leads to the next one. The tasks of the test battery try to examine elementary processes of the human performance apparatus; the probationer's answer is usually arranged as single reaction, choice response or tracking. We will now describe individual task types from the test battery:

SRT, Single Reaction Task:The subjects are to react as quickly as possible to a stimulus that is offered in arbitrary intervals on the screen; the response time is measured. In a special variant task according to Dinges, the stimulus is a digital stop watch counting up that will - after the response has taken place - show the time achieved for 3 seconds. After the arbitrary interval, during which the screen stays blank, the next stop watch run appears. Here, attention and vigilance are primarily needed.

MST, Memory Search Task:Following the Sternberg-paradigm, the probationers are to memorize a number of letters shown in the preparatory stage. After the task has started, a letter is shown on the screen. Using two keys to answer, the probationer is to decide if the letter belongs to the memorized letters or not. After an answer, the next letter directly appears. With a rising number of letters, the reaction span grows longer. The task investigates the functioning of the working memory and of the short time memory.

GRT, Grammatical Reasoning Task:With this taks, a group of three symbols whose sequence changes from question to question is offered, e.g. "*&#". The first two lines on the screen show linguistic statements concerning the sequence of the symbols in the third line, e.g. "& is in front of *", "'# comes after &". The probationer determines the truth value of the statements and uses the "Equal" key if both statements are correct or incorrect and the "Not Equal" key if one statement is true and the other one is wrong (in our example, the truth value is not equal). Aftter an answer has been given, the next question appears. This task tests the processing of more complex mental procedures.

UTT, Unstable Tracking Task:In the center of the screen, a cursor appears. The cursor is directed to the side by the program. The farther the cursor is already distanced from the center position, the faster it is directed to the side. Using a joystick, the probationer is to keep the cursor in the center position as well as possible; the distance to the center position and the number of control losses (the cursor reaches the sideline of the screen) are logged. This task investigates hand-eye-coordination as well as the sensorimotor function and is typical for operator activities in technical systems.

DUT, Dual Task:

With this task, MST and UTT are presented simultaneously. The probationer has to respond by choice reaction keys to the letters shown and has to keep the cursor in central position with the joystick at the same time. This task tests the reserve capacity under multiple pressure.

The individual tasks test different aspects of performance. It is necessary to investigate, which type of task is most appropriate for a sensitive assessment of the different stressors.